常用sql收藏

新增字段IsCheckInvoice

  Alter table T_LegalUnit add IsCheckInvoice bit

UPDATE T_LegalUniT   SET IsCheckInvoice=1 WHERE LegalUnitID='000010'
 SELECT *FROM T_LegalUnit WHERE IsCheckInvoice=1

1.查询表中重复字段

 SELECT  MOBILE_PHONE FROM T_Saas_Device  GROUP BY MOBILE_PHONE,CompanyGUID HAVING COUNT(*)>1

重复数据,保留uid最小的数据

create database Test
use Test

if OBJECT_ID('users','U') is not null
drop  table users
go
create table users(
  uid int identity(1,1) primary key  ,
  uname varchar(50) not null,
  uemail  varchar(50) not null,
  sex char(2) not null ,
  createtime  datetime not null
)


insert into users (uname,uemail,sex,createtime)values('张筱雨','mi@163.com','女',getdate());
insert into users (uname,uemail,sex,createtime)values('王旭','wangxu@163.com','男',getdate());
insert into users (uname,uemail,sex,createtime)values('张晓','zhangxiao@163.com','女',getdate());
insert into users (uname,uemail,sex,createtime)values('刘小雨','xiaoyu@163.com','女',getdate());
insert into users (uname,uemail,sex,createtime)values('李青','liqing@163.com','男',getdate());
insert into users (uname,uemail,sex,createtime)values('肖珂','xiaoke@163.com','女',getdate());
insert into users (uname,uemail,sex,createtime)values('张西','zhangxi@163.com','男',getdate());
insert into users (uname,uemail,sex,createtime)values('程旭','chengxu@163.com','男',getdate());


insert into users (uname,uemail,sex,createtime)values('小明','wang@163.com','男',getdate());
insert into users (uname,uemail,sex,createtime)values('小明','wang@163.com','男',getdate());


select *from users

第一种写法

delete u from users u
where exists(select *from 
(select uname from users group by uname having count(uname)>1)as s
where u.uname=s.uname)
and u.uid not in (select min(uid) from users group by uname )

第二种写法

delete from users  where uid not in(
select uid from users a where not exists (
select 1 from users b where a.uname = b.uname and  b.uid < a.uid ))

查询重复的用户名

select *from users
where uname in(select uname from users group by uname having count(*)>1)

查询重复的用户名次数和记录

select count(*)as 重复次数,uname from users group by uname having count(*)>1

查找表中多余的重复记录，重复记录是根据单个字段（uname）来判断

 select *from users 
 where uname in(select uname from  users group by uname having count(uname)>1)

查找表中多余的重复记录（多个字段）

select *from users u where exists
(select *from (select uname,uemail from users group by uname,uemail having count(*)>1)as s 
where u.uname=s.uname and u.uemail=s.uemail)

查找表中多余的重复记录（多个字段），不包含rowid最小的记录

select *from users u
where exists(select *from 
(select uname,uemail from users group by uname,uemail having count(*)>1)as s 
where u.uname=s.uname and u.uemail=s.uemail)
and u.uid not in(select min(uid)from users group by uname,uemail)

两条相同的记录 ，查询只有uname相同的数据

 select *from users where uname in(select uname from users group by uname having count(uname)>1)

两条相同的记录 ，查询只有uname,uemail相同的数据

select *from users u where exists(select *from 
(select uname,uemail from users group by uname,uemail having count(*)>1 )as s
where u.uname=s.uname and u.uemail=s.uemail)order by uname desc

删除表中多余的重复记录，重复记录是根据单个字段（uname）来判断，只留有uid最小的记录

delete u from users u where exists (select *from
(select uname from users group by uname having count(*)>1)as s 
where u.uname=s.uname )
and u.uid not in(select min(uid)from users group by uname )


delete from users  where uid not in(
select uid from users a where not exists (
select 1 from users b where a.uname = b.uname and  b.uid < a.uid 
));

删除表中多余的重复记录（多个字段），只留有rowid最小的记录

 delete u from users u where exists(select *from 
 (select uname,uemail from users group by uname,uemail having count(*)>1)as s 
 where u.uname=s.uname and u.uemail=s.uemail)
  and u.uid not in(select min(uid)from users group by uname,uemail)

常用sql收藏

原文：https://www.cnblogs.com/imtudou/p/11251910.html